This is book 1 of the "Miles Vorkosigan" series.

This note contains spoilers for the book.

The first Miles book (in publication order). He fails to qualify for the Academy by making an emotional decision in the obstacle course, goes off to Beta to visit his grandmother and recover (from the two broken legs), and stumbles into various things and invents the Dendari Mercenaries.

I haven't reread this one in far too long; recently I think I was afraid it wouldn't hold up, but I'm not sure what kept me away earlier. Because I remember this and the first book in that universe really grabbing my attention when they first came out. Anyway, it does stand up, very well indeed. Lots of things I associate with Miles later on are clearly well established here—from "forward momentum" on. Also his amazing ability to pick personnel, and to get people to really work for him. And his very careful body language.

This one includes Elena saying she loves him and cannot possibly stay around him (he annexes people, she thinks; which is entirely true). And Eli Quinn losing her old face. And the plot against his father based on his intending to rebel using his private army (technically treason, but it hadn't occurred to him since he was off-planet and had no interest in the throne).

So I'm very glad indeed I finally decided to reread this.